AURORA, Co. (Reuters) - President Barack Obama's re-election team, maintaining an unofficial time-out on full-scale campaigning following a deadly shooting at a movie theater, said on Sunday it will keep its advertisements off the airwaves in Colorado for the rest of the week.

Obama and his Republican rival Mitt Romney both set aside the previously harsh tone of the November 6 election campaign to speak soothingly to the nation on Friday, after the shooting rampage that killed 12 at a midnight movie screening outside Denver.

That prompted speculation about whether the tragedy may have a lasting impact in terms of softening what is widely seen as one of the nastiest election fights in recent memory.

Obama campaign spokeswoman Jen Psaki said the ads would be kept off the airwaves in Colorado until the end of this week, but was unclear for how much longer the Obama re-election team would keep its activities throttled back.

"Just like everybody, we're taking this day-by-day. It is too early to say, on the specific policy issues, what that will mean," Psaki told reporters traveling with Obama.

Obama was visiting victims and families of the Friday night shooting and will make a short statement to the press later on Sunday before traveling to San Francisco, where he will begin a scheduled 3-day swing of fundraising and official events.

But he has canceled a grassroots rally in Portland, Oregon on Tuesday, in part out of respect to victims of the shooting, Psaki said. Those grassroots events tend to be raucous and highly partisan, and cancelling it was seen as the right thing to do, given the nature of the tragedy, she said.

The second reason was that resources involved in staffing a presidential visit, including Secret Service teams to protect Obama and move him around, had to be diverted to Colorado on short notice to allow him to pay his respects.

(Reporting By Alister Bull; editing by Todd Eastham)